Endotracheal intubation (ETI) is the medical procedure in which a tube is inserted into the trachea of a patient to facilitate breathing or to permit the controlled introduction of gases through the tube. Because the trachea is parallel and anterior to the esophagus, and is normally closed off by the epiglottis, a tube simply introduced orally or nasally will likely travel to the esophagus rather than the trachea. To place the tube through a patient's larynx and into the trachea, it is necessary to displace the epiglottis and other soft tissues which normally obstruct the glottic opening. Additionally, if the patient is not breathing independently, the procedure must be done within approximately 60 seconds to avoid complications due to potentially fatal oxygen deprivation.
Endotracheal intubation can be accomplished by several methods that can be categorized as blind, direct, or endoscopic. Blind methods are those in which the intubator does not see the trachea during the intubation process. These methods include nasotracheal, tactile digital, illuminated stylet, and various doublelumen tube intubations. They are useful when the trachea is hopelessly obscured from view such as during copious bleeding to the larynx. However, blind methods do not offer high success rates, nor do they allow the intubator to confirm the correct placement of the endotracheal tube visually, a serious drawback.
Endoscopic methods make use of a fiberoptic endoscope a miniature lens on the end of a long, thin, fiberoptic bundle. The intubator remotely manipulates the distal end and endotracheal tube into the trachea while viewing through the eye piece at the proximal end. Endoscopic methods are advantageous in that they do allow visual confirmation of proper tube placement. However, they require a significant amount of training and skill, and are expensive, making them financially inaccessible for most ambulance companies and many emergency departments. Hence, endoscopes are not widely used for intubation.
The majority of intubations are performed by direct methods, employing various shaped laryngoscopes, most commonly the Macintosh and Miller blades. Direct methods involve manually retracting the soft tissues and lifting the epiglottis until the trachea can be viewed directly. The endotracheal tube is then manually introduced and proper placement visually confirmed. Direct laryngoscopic intubation (DLI) is the most commonly employed technique in the United States since the equipment needed is affordable and training required moderate.
Direct laryngoscopic intubation is accomplished by performing several steps. Prior to attempting these steps, an oral airway (OA) is commonly inserted into the pharynx to open the airway by lifting the tongue from the posterior pharyngeal wall. Temporizing methods of ventilation are commonly employed such as BVM (bag-valve-mask ) ventilation while the intubation equipment is prepared. Briefly the steps of DLI are: 1. stopping ventilation; 2. removing oral airway; 3. opening patient's mouth; 4. differentiating soft tissues; 5. inserting laryngoscope; 6. positioning laryngoscope; 7. retracting via lifting including lifting the epiglottis; 8. visualizing the trachea; 9. inserting endotracheal tube into trachea.
Novice and infrequent intubators commonly experience difficulty with several DLI steps including opening the patient's mouth and inserting the laryngoscope. Inserting an oral airway is a comparatively simple process. The OA is inserted into a minimally opened mouth and slid blindly along the hard palate until the proximal end is seated against the lips, teeth, and other underlying anterior oral structures. The OA is of soft material and thus poses little chance of inflicting trauma such as lacerations or broken teeth. Inserting a laryngoscope, however, is more complex as the mouth must be widely opened; the laryngoscope is made of metal which can more easily cause trauma; and the insertion process cannot be initiated until after the soft tissues have been differentiated correctly.
Insertion of the laryngoscope is further complicated because the trachea is deep and anterior in the pharynx and lies at an approximate 90-degree angle to the oral cavity. Further, in the unconscious patient, the tongue collapses, falling against the posterior pharyngeal wall and the hard palate. The intubator's task is to insert the blade between the tongue and hard palate, advance the tip first posteriorly then inferiorly to the posterior aspect of the tongue, and then advance inferiorly almost to the epiglottis. Being of very soft consistency, the tongue tends to collapse around both sides of the blade and be carried in the direction of the blade's movement. To avoid pushing the tongue further into the throat, the intubator must employ an iterative process of placing the laryngoscope against the tongue, blindly advancing posteriorly, retracting the tongue anteriorly to allow visualization of the current distal tip position, then further blindly advancing. This is continued until the epiglottis can be visualized.
Also, intubators often have difficulty positioning the laryngoscope properly. Improper placement leads to certain failure as epiglottic lifting requires very exact positioning of the distal blade tip to within 0.5-1.0 cm of the target position. However, obtaining the target position for the distal blade tip is difficult because it cannot even be seen until the final movement iteration. Also, there may be blood, vomitus, teeth or other foreign matter obscuring the view; the entire area of focus is rather small, as the tongue tends to collapse around the blade, and thus finding the proper location for the blade tip can be very difficult.
Another difficulty is developing the proper lifting motion. The natural tendency to pivot the laryngoscope like a lever makes success highly unlikely and promotes oral trauma. The proper motion involves a translational movement at approximately 45-60 degrees to the patient's trachea. "Lifting" requires the intubator to apply approximately 20-30 lbs. of force with a fully outstretched arm and to maintain this position for the remainder of the procedure. This must be held steadily, as wavering will cause the pharynx to move with the laryngoscope. It is a physically demanding yet delicate step to hold such an awkward position while applying a steady force. Further, even minimal variance from the required motion, or minimal rotation of the blade will make visualization of the trachea impossible.
Problems also arise when the intubation attempt fails. If the attempt is not completed within approximately 60 seconds (for example: inability to visualize the trachea, improper lifting motion, inability to hold the lifting position long enough to allow tube placement, inability to find the epiglottis amongst the soft tissues, inability to pass the tube into the trachea), it must be aborted. Subsequently, the laryngoscope is withdrawn, the oral airway reinserted, and the patient ventilated for 2-3 minutes (to obtain sufficient systemic oxygenation) before a second attempt can be initiated. The disadvantages of a failed attempt include the 2-3 minute time delay before the second attempt can be initiated, but even more notably, all of the steps successfully performed in the first attempt must be repeated during the second attempt since each attempt begins the process anew.
These commonly encountered problems are inherent in the design of the currently available equipment for DLI, making intubation a heavily skill-dependent process that relies upon the individual intubator's abilities for success.
The prior art shows some attempts at solving the needs of the less experienced intubator. U.S. Pat. No. 5,498,231 to Franicevic discloses an intubating laryngoscope having two blades which pivot about separate axes and a lever to move the ends of the blades apart. Because the device completely blocks the field of view, an optical system and a fiberoptic illumination system are necessary for viewing. The movement of the blades in this device is "beak-like" and inconsistent with movement of the human body. The device is rather complicated and requires many elements which would be too expensive for inclusion on many emergency vehicles.
U.S. Pat. No. 5,178,132 to Mahefky discloses a laryngoscope which employs the chin of a patient as a reference fulcrum for enabling controlled pivotal movement of a laryngeal blade. While this device is designed to prevent injury, it does not assist the intubator in maintaining the mouth in an open position, nor does it provide a means for viewing the airway.
U.S. Pat. No. 4,793,327 to Frankel discloses a mouth-holding device having a lower and an upper arm. An esophageal guide passes through a bracket which is attached to the upper arm. The lower arm includes notches adapted to receive a catch of the upper arm. An adapter on the guide allows for the insertion of an endotracheal tube having an adapter sized to mate with the guide's adapter. While the guide allows for blind insertion, the device does not press the tissue within a patient's mouth in a manner which opens the airway, does not provide for visualization within the patient's mouth, and requires specially designed endotracheal tubes which may not be readily available.
Thus, there is a need for a device which can assist an intubator in easily and quickly accomplishing direct laryngoscopic intubation. There is further a need for such a device which is inexpensive enough to be financially accessible for any emergency vehicle. There is further a need for such a device which enables indirect visualization of a patient's airway. There is further a need for such a device which performs the skill-required steps of the intubation process. There is further a need for a device which provides hands-free, stable retraction for insertion of the endotracheal tube. There is further a need that such a device fit entirely beneath a standard airway mask in order that intubation can always be achieved in a single attempt.